1. Field of the Invention
The present invention relates to a sheet bending apparatus which bends a sheet in a standing state, and to a stapling apparatus which staples stacked sheets that are changed from a horizontally lying state to a standing state.
2. Description of the Related Art
Generally, as an example of paperwork carried out with a relatively high frequency, there is a work to produce a booklet. In such a work, a set of sheets is formed by stapling sheets having thereon images formed by an image forming device such as printers and copying machines, and the set of sheets is bent in two, thereby a booklet is produced. As an apparatus for easily carrying out such a work, there is proposed an apparatus which forms a set of sheets by stapling sheets and bending the stapled set in two (see Japanese Patent Application Publication No. 11-322172 for example).
The apparatus shown in Japanese Patent Application Publication No. 11-322172 is provided with a storage system for storing sheets in a standing state that are sequentially transferred along predetermined transfer paths arranged in the apparatus. This storage system vertically moves the sheets stored in a standing state and is provided with a stapler for performing stapling processing and a bending system for performing bending processing within a range of the movement of the sheets. The stapler has a staple feeding opening for feeding a staple while holding the sheets stacked in a standing state and staples the sheets while holding a predetermined position of the sheets such as the center thereof in the feeding opening. In addition, the bending system includes a pushing member laterally extending and intersecting the vertical direction of the standing sheets and causes the pushing member to push a predetermined position of the sheets such as the center thereof to bend the sheets into two. The storage system moves the sheets stored in a standing state for a predetermined distance until the predetermined position of the sheets reaches a position in the staple feeding opening and in front of the pushing member of the bending system.
Incidentally, an apparatus of this type uses various kinds of sheets different in flexural rigidity due to difference in thickness. For example, there is used a relatively thin and less rigid sheet such as coated paper whose image-formed surface has been subjected to a surface treatment. This type of sheets may be stored in the storage system while remaining flexed by the self weight. As a result, the predetermined position of the sheets may not be aligned with the staple feeding position and the pushing member of the bending system, resulting in a defect such as stapling and bending at a position other than the predetermined position.